Environmental review documents for the Bay Delta Conservation Plan will not be ready for release by the end of June as originally planned, the Natural Resources Agency announced Friday.

In a letter to the U.S. Department of the Interior, Natural Resources Secretary John Laird said there will be “some workable delays” in the release of the documents.

“From the outset, we have all agreed that science should drive the design of the project and our plans for its implementation,” Laird wrote to Deputy Interior Secretary David Hayes. “The fish and wildlife agencies are currently reviewing and responding to a substantially improved scientific analysis of habitat restoration, water flows, and other ecological measures to achieve regulatory standards of the federal Endangered Species Act and Natural Community Conservation Planning Act. As a result, we anticipate that we will soon be able to announce some significant adjustments in the overall program that will reflect our commitment to using the best science.

“This should not interfere in any way with our preparations for a public announcement of the key elements of a framework for the proposed project with the Governor and Secretary Salazar in mid-to-late July. Unfortunately, it does mean we will not be ready to release public review drafts of BDCP and its environmental impact report/statement at the end of June.”

The State Water Contractors association voiced concern with the delay.

“During the past six years, state and federal agencies have compiled the best available science on the Delta. It is deeply troubling that, even with the substantial financial and scientific resources provided, the federal agencies are unable to make the decisions necessary to protect the water supply for 25 million Californians and protect the Delta environment,” Terry Erlewine, general manager of the State Water Contractors, said in a statement.

ACWA also expressed concern.

“While we recognize the complexity of the process, we are concerned to see any significant delay in making the decisions needed to improve water supply reliability and restore the Delta ecosystem," ACWA Executive Director Timothy Quinn said. "Since many other processes hinge on information being developed as part of the BDCP, it’s critical that this planning effort move forward.”